[vlc-devel] VLC dying when transcoding and resizing stream

[Michael Ditum]

Hi,

I'm seeing a problem when using VLC to re-encode a video stream. The input
stream is an MPEG-2 TS multicast stream of BBC One London (though I can get
the same thing to happen with big_buck_bunny_720p_stereo.ogg so I don't
think it's an input problem). I'm then converting it to h254 at 960x540
with a video bitrate of 1800. Finally I'm streaming the converted stream to
a multicast address. The command I'm using is...

vlc -I dummy --verbose=3 --color
udp://@239.72.0.0:1234':sout=#duplicate{dst="transcode{threads=2,width=960,height=540,fps=25,vcodec=h264,vb=1800,venc=x264{aud,profile=baseline,level=30,keyint=30,bframes=0,ref=1,nocabac},acodec=aac,ab=40}:standard{access=udp{port=1234,miface=lo},mux=ts,dst=239.51.88.6}"}'

What I'm seeing is that the video will convert and stream fine for a little
while (generally between 10 and 30 seconds, though every now and then it
will last for a couple of minutes) and then die. The way it dies varies
depending on the version of software I'm using.

*VLC 2.0.0, with ffmpeg 0.10 and an x264 git snapshot from 2011-10-31*
With this setup it will stream for a while and then the multicast output
will stop, the CPU usage will drop considerably (implying that the actual
transcoding has stopped) however if I leave it for a while I can see dvbpsi
messages about XXX. When it dies I get the following type of messages:

[0xb5205a88] access_output_udp access out debug: late packet for UDP input
(870951)
[0xb5205a88] access_output_udp access out debug: late packet for UDP input
(867002)
[0xb5205a88] access_output_udp access out debug: late packet for UDP input
(863041)
x264 [warning]: internal error (MV out of thread range)
x264 [warning]: recovering by using intra mode
[0xb5205a88] access_output_udp access out debug: packet has been sent too
late (1019555)
x264 [error]: Input picture width (960) is greater than stride (544)
[0xb5205a88] access_output_udp access out debug: late packet for UDP input
(859091)
[0xb5205a88] access_output_udp access out debug: packet has been sent too
late (1019234)
[0xb5205a88] access_output_udp access out debug: packet has been sent too
late (1015323)
x264 [warning]: internal error (MV out of thread range)
x264 [warning]: internal error (MV out of thread range)
x264 [warning]: recovering by using intra mode
x264 [warning]: internal error (MV out of thread range)
x264 [warning]: recovering by using intra mode
x264 [warning]: internal error (MV out of thread range)
x264 [warning]: recovering by using intra mode
x264 [warning]: internal error (MV out of thread range)
x264 [warning]: recovering by using intra mode
x264 [warning]: internal error (MV out of thread range)
x264 [warning]: recovering by using intra mode

*VLC master git, FFMPEG master git and x264 master git all from yesterday
afternoon*
With this setup it will stream for a while and then VLC will seg fault. You
don't get a period where it stops transcoding but VLC is still running like
you do with vlc 2.0.0.

When it dies you get messages like the following:
[0x80cc1a8] access_output_udp access out debug: packet has been sent too
late (29413565)
[0x80cc1a8] access_output_udp access out debug: packet has been sent too
late (29406435)
[0x80cc1a8] access_output_udp access out debug: packet has been sent too
late (29399305)
[0x80cc1a8] access_output_udp access out debug: packet has been sent too
late (29392175)
[0x80cc1a8] access_output_udp access out debug: packet has been sent too
late (29385046)
[0x80cc1a8] access_output_udp access out debug: packet has been sent too
late (29377921)
[0x80cc1a8] access_output_udp access out debug: packet has been sent too
late (29370793)
[0x80ccd58] main mux warning: late buffer for mux input (30373100)
[0x80ccd58] main mux warning: late buffer for mux input (146514)
[0x80ccd58] main mux warning: late buffer for mux input (130690)
[0x80ccd58] main mux warning: late buffer for mux input (110274)
[0x80ccd58] main mux warning: late buffer for mux input (140198)
[0x80ccd58] main mux warning: late buffer for mux input (136323)
[0x80ccd58] main mux warning: late buffer for mux input (133104)

At times in this setup I'll also see the x264 errors "internal error (MV
out of thread range) recovering by using intra mode" and "Input picture
width (960) is greater than stride (544)", which I get relatively regularly
with vlc 2.0.0. If I lower the width and height of the outputed video so
the width is 544 (and the height is proportionate) then vlc will happily
convert the video for hours on end.

I've captured a number of log files:
http://pastebin.com/NkhhEyFU is the output of the problem occuring using
vlc 2.0.0.
http://pastebin.com/Lsf3S04M is using the git versions and where it died
almost straight away

Does anyone know what could be causing this problem?
Is this a mis-configuration from me or a bug in VLC / x264? (the seg fault
seems like a bug to me)
Is there any way of specifying this "stride" in x264 so it's larger?
Is there anything extra I can do to provide extra debugging information to
help fix this issue?

Thanks in advance for all your help!

Mike
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